In Chinese summer, ancient Chinese divided it into three periods: slight heat, great heat and the Limit of Heat.

The three periods of the hot season refer to the hottest days of the year, which usually come between late July and mid-August, because after Summer Solstice, daytime is becoming shorter and shorter while nights are longer and longer. The heat absorbed by the earth is much more than that radiated. The temperature near the earth gets higher and higher. When the hot season comes, the heat absorbed by the earth is almost less than that radiated, and the weather reaches its hottest period of the year.

Weather in Major Heat is the hottest part of the year. According to ancient records, it is actually scorching heat during the Major Heat period. That’s because the heat absorbed by the earth in the daytime is more than that radiated at night, and the heat accumulated day by day reaches its peak during Major Heat.

The first and second periods of the hot season of a year cover the Major Heat period, while the third period comes after autumn begins. One thing they have in common is that the weather is extremely hot.